package UDP;

import java.io.IOException;
import java.net.*;
import java.util.Scanner;

public class UdpEchoClient {
    private DatagramSocket socket=null;
    private String ServerIP;
    private int ServerPort;
    public UdpEchoClient(String ServerIP,int ServerPort) throws SocketException {
        socket=new DatagramSocket();
        this.ServerIP=ServerIP;
        this.ServerPort=ServerPort;
    }
    public void start() throws IOException {
        System.out.println("启动客户端！");
        Scanner in=new Scanner(System.in);

        while (true){
            //1、从控制台读取用户输入
            System.out.println("-> ");
            String request=in.next();
            //2、构造出一个UDP请求
            DatagramPacket requestPacket=new DatagramPacket(request.getBytes(),request.getBytes().length, InetAddress.getByName(this.ServerIP),this.ServerPort);
            socket.send(requestPacket);
            //3、从服务器读取到响应
            DatagramPacket responsePacket=new DatagramPacket(new byte[4096],4096);
            socket.receive(responsePacket);
            String response=new String(responsePacket.getData(),0,responsePacket.getLength());
            //4、把响应打印到控制台上
            System.out.println(response);
        }
    }

    public static void main(String[] args) throws IOException {
        UdpEchoClient client=new UdpEchoClient("127.0.0.1",9090);
        client.start();
    }
}
